Hemmed structure and hemming method

Abstract

A hemmed structure includes a first member and a second member. The first member is a sheet-like member including a thermoplastic resin and includes an inner bent portion formed at a position at which an end portion of the first member is bent. The second member is a sheet-like member a metal material and includes an outer bent portion formed at a position at which an end portion of the second member is bent. The outer bent portion is disposed so as to wrap around the inner bent portion, and the end portion of the second member is disposed inside the inner bent portion. A brittle portion is formed on an inner surface of the inner bent portion.

The invention claimed is: 
     
       1. A hemmed structure comprising:
 a first member that is a sheet-like member including a thermoplastic resin, the first member including an inner bent portion formed at a position at which an end portion of the first member is bent; and 
 a second member that is a sheet-like member including a metal material, the second member including an outer bent portion formed at a position at which an end portion of the second member is bent; 
 wherein the outer bent portion is disposed so as to wrap around the inner bent portion, and the end portion of the second member is disposed inside the inner bent portion; 
 wherein a thinned portion is formed on an inner surface of the inner bent portion; and 
 wherein the second member includes an end portion which includes two substantially parallel flanges joined by a back-bend proximate to the inner bent portion of the first member. 
 
     
     
       2. The hemmed structure according to  claim 1 ,
 wherein the back-bend proximate to the inner bent portion of the first member is a sharp back-bend. 
 
     
     
       3. The hemmed structure according to  claim 2 ,
 wherein the thinned portion is a recess formed by heating and pressing the first member with a pressing member. 
 
     
     
       4. The hemmed structure according to  claim 3 ,
 wherein the thermoplastic resin is a fiber-reinforced plastic. 
 
     
     
       5. The hemmed structure according to  claim 2 ,
 wherein the thermoplastic resin is a fiber-reinforced plastic. 
 
     
     
       6. The hemmed structure according to  claim 1 ,
 wherein the thinned portion is a recess formed by heating and pressing the first member with a pressing member. 
 
     
     
       7. The hemmed structure according to  claim 6 ,
 wherein the thermoplastic resin is a fiber-reinforced plastic. 
 
     
     
       8. The hemmed structure according to  claim 1 ,
 wherein the thermoplastic resin is a fiber-reinforced plastic. 
 
     
     
       9. A hemming method for making a hemmed structure, the method comprising:
 a placement step of placing a first member and a second member one on top of the other so that an end portion of the first member and an end portion of the second member are displaced from each other, the first member including a thermoplastic resin and having a sheet-like shape, and a second member including a metal material and having a sheet-like shape; 
 a first bending step of bending the end portion of the second member so as to wrap around the end portion of the first member; 
 a press heating step of forming a thinned portion in the first member by pressing and heating either one of the first member and the second member at a position near the end portion of the second member with the first member and the second member one on top of the other; and 
 a second bending step of bending the first member and the second member at the thinned portion so that the end portion of the first member is disposed inside the second member, wherein the second bending step results in the end portion of the second member including two substantially parallel flanges joined by a back-bend proximate to the position of the press heating step.